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coreboot-kgpe-d16/src/lib/libgcc.c

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src/lib: Use SPDX for GPL-2.0-only files Done with sed and God Lines. Only done for C-like code for now. Change-Id: Id3a0b63272ebda3dad13803700bcff36d36f4815 Signed-off-by: Angel Pons <th3fanbus@gmail.com> Reviewed-on: https://review.coreboot.org/c/coreboot/+/40054 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
2020-04-02 23:48:34 +02:00
/* SPDX-License-Identifier: GPL-2.0-only */
lib: Unify log2() and related functions This patch adds a few bit counting functions that are commonly needed for certain register calculations. We previously had a log2() implementation already, but it was awkwardly split between some C code that's only available in ramstage and an optimized x86-specific implementation in pre-RAM that prevented other archs from pulling it into earlier stages. Using __builtin_clz() as the baseline allows GCC to inline optimized assembly for most archs (including CLZ on ARM/ARM64 and BSR on x86), and to perform constant-folding if possible. What was previously named log2f on pre-RAM x86 is now ffs, since that's the standard name for that operation and I honestly don't have the slightest idea how it could've ever ended up being called log2f (which in POSIX is 'binary(2) LOGarithm with Float result, whereas the Find First Set operation has no direct correlation to logarithms that I know of). Make ffs result 0-based instead of the POSIX standard's 1-based since that is consistent with clz, log2 and the former log2f, and generally closer to what you want for most applications (a value that can directly be used as a shift to reach the found bit). Call it __ffs() instead of ffs() to avoid problems when importing code, since that's what Linux uses for the 0-based operation. CQ-DEPEND=CL:273023 BRANCH=None BUG=None TEST=Built on Big, Falco, Jerry, Oak and Urara. Compared old and new log2() and __ffs() results on Falco for a bunch of test values. Change-Id: I599209b342059e17b3130621edb6b6bbeae26876 Signed-off-by: Patrick Georgi <pgeorgi@chromium.org> Original-Commit-Id: 3701a16ae944ecff9c54fa9a50d28015690fcb2f Original-Change-Id: I60f7cf893792508188fa04d088401a8bca4b4af6 Original-Signed-off-by: Julius Werner <jwerner@chromium.org> Original-Reviewed-on: https://chromium-review.googlesource.com/273008 Original-Reviewed-by: Patrick Georgi <pgeorgi@chromium.org> Reviewed-on: http://review.coreboot.org/10394 Tested-by: build bot (Jenkins) Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
2015-05-23 01:26:40 +02:00
#include <types.h>
/*
* Provide platform-independent backend implementation for __builtin_clz() in
* <lib.h> in case GCC does not have an assembly version for this arch.
*/
treewide: Replace CONFIG(ARCH_xx) tests Once we support building stages for different architectures, such CONFIG(ARCH_xx) tests do not evaluate correctly anymore. Change-Id: I599995b3ed5c4dfd578c87067fe8bfc8c75b9d43 Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com> Reviewed-on: https://review.coreboot.org/c/coreboot/+/42183 Reviewed-by: Raul Rangel <rrangel@chromium.org> Reviewed-by: Furquan Shaikh <furquan@google.com> Reviewed-by: Angel Pons <th3fanbus@gmail.com> Reviewed-by: Aaron Durbin <adurbin@chromium.org> Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
2020-06-08 05:05:03 +02:00
/*
* FIXME
* work around lack of --gc-sections on x86
* defined in rv32 libgcc.a
*/
#if !ENV_X86 && !ENV_RISCV
lib: Unify log2() and related functions This patch adds a few bit counting functions that are commonly needed for certain register calculations. We previously had a log2() implementation already, but it was awkwardly split between some C code that's only available in ramstage and an optimized x86-specific implementation in pre-RAM that prevented other archs from pulling it into earlier stages. Using __builtin_clz() as the baseline allows GCC to inline optimized assembly for most archs (including CLZ on ARM/ARM64 and BSR on x86), and to perform constant-folding if possible. What was previously named log2f on pre-RAM x86 is now ffs, since that's the standard name for that operation and I honestly don't have the slightest idea how it could've ever ended up being called log2f (which in POSIX is 'binary(2) LOGarithm with Float result, whereas the Find First Set operation has no direct correlation to logarithms that I know of). Make ffs result 0-based instead of the POSIX standard's 1-based since that is consistent with clz, log2 and the former log2f, and generally closer to what you want for most applications (a value that can directly be used as a shift to reach the found bit). Call it __ffs() instead of ffs() to avoid problems when importing code, since that's what Linux uses for the 0-based operation. CQ-DEPEND=CL:273023 BRANCH=None BUG=None TEST=Built on Big, Falco, Jerry, Oak and Urara. Compared old and new log2() and __ffs() results on Falco for a bunch of test values. Change-Id: I599209b342059e17b3130621edb6b6bbeae26876 Signed-off-by: Patrick Georgi <pgeorgi@chromium.org> Original-Commit-Id: 3701a16ae944ecff9c54fa9a50d28015690fcb2f Original-Change-Id: I60f7cf893792508188fa04d088401a8bca4b4af6 Original-Signed-off-by: Julius Werner <jwerner@chromium.org> Original-Reviewed-on: https://chromium-review.googlesource.com/273008 Original-Reviewed-by: Patrick Georgi <pgeorgi@chromium.org> Reviewed-on: http://review.coreboot.org/10394 Tested-by: build bot (Jenkins) Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
2015-05-23 01:26:40 +02:00
int __clzsi2(u32 a);
int __clzsi2(u32 a)
{
static const u8 four_bit_table[] = {
[0x0] = 4, [0x1] = 3, [0x2] = 2, [0x3] = 2,
[0x4] = 1, [0x5] = 1, [0x6] = 1, [0x7] = 1,
[0x8] = 0, [0x9] = 0, [0xa] = 0, [0xb] = 0,
[0xc] = 0, [0xd] = 0, [0xe] = 0, [0xf] = 0,
};
int r = 0;
lib/libgcc.c: Fix shift warnings ``` if (!(a & (0xffff << 16))) { ^~ src/lib/libgcc.c:40:18: error: result of '255 << 24' requires 33 bits to represent, but 'int' only has 32 bits [-Werror=shift-overflow=] if (!(a & (0xff << 24))) { ^~ src/lib/libgcc.c:45:17: error: result of '15 << 28' requires 33 bits to represent, but 'int' only has 32 bits [-Werror=shift-overflow=] if (!(a & (0xf << 28))) { ^~ ``` Change-Id: I7bdd75c20a76b303743d7e7e0d3a6503760284fd Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de> Reviewed-on: https://review.coreboot.org/c/23361 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Patrick Rudolph <siro@das-labor.org> Reviewed-by: Julius Werner <jwerner@chromium.org> Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
2018-01-23 00:13:57 +01:00
if (!(a & (0xffffU << 16))) {
lib: Unify log2() and related functions This patch adds a few bit counting functions that are commonly needed for certain register calculations. We previously had a log2() implementation already, but it was awkwardly split between some C code that's only available in ramstage and an optimized x86-specific implementation in pre-RAM that prevented other archs from pulling it into earlier stages. Using __builtin_clz() as the baseline allows GCC to inline optimized assembly for most archs (including CLZ on ARM/ARM64 and BSR on x86), and to perform constant-folding if possible. What was previously named log2f on pre-RAM x86 is now ffs, since that's the standard name for that operation and I honestly don't have the slightest idea how it could've ever ended up being called log2f (which in POSIX is 'binary(2) LOGarithm with Float result, whereas the Find First Set operation has no direct correlation to logarithms that I know of). Make ffs result 0-based instead of the POSIX standard's 1-based since that is consistent with clz, log2 and the former log2f, and generally closer to what you want for most applications (a value that can directly be used as a shift to reach the found bit). Call it __ffs() instead of ffs() to avoid problems when importing code, since that's what Linux uses for the 0-based operation. CQ-DEPEND=CL:273023 BRANCH=None BUG=None TEST=Built on Big, Falco, Jerry, Oak and Urara. Compared old and new log2() and __ffs() results on Falco for a bunch of test values. Change-Id: I599209b342059e17b3130621edb6b6bbeae26876 Signed-off-by: Patrick Georgi <pgeorgi@chromium.org> Original-Commit-Id: 3701a16ae944ecff9c54fa9a50d28015690fcb2f Original-Change-Id: I60f7cf893792508188fa04d088401a8bca4b4af6 Original-Signed-off-by: Julius Werner <jwerner@chromium.org> Original-Reviewed-on: https://chromium-review.googlesource.com/273008 Original-Reviewed-by: Patrick Georgi <pgeorgi@chromium.org> Reviewed-on: http://review.coreboot.org/10394 Tested-by: build bot (Jenkins) Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
2015-05-23 01:26:40 +02:00
r += 16;
a <<= 16;
}
lib/libgcc.c: Fix shift warnings ``` if (!(a & (0xffff << 16))) { ^~ src/lib/libgcc.c:40:18: error: result of '255 << 24' requires 33 bits to represent, but 'int' only has 32 bits [-Werror=shift-overflow=] if (!(a & (0xff << 24))) { ^~ src/lib/libgcc.c:45:17: error: result of '15 << 28' requires 33 bits to represent, but 'int' only has 32 bits [-Werror=shift-overflow=] if (!(a & (0xf << 28))) { ^~ ``` Change-Id: I7bdd75c20a76b303743d7e7e0d3a6503760284fd Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de> Reviewed-on: https://review.coreboot.org/c/23361 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Patrick Rudolph <siro@das-labor.org> Reviewed-by: Julius Werner <jwerner@chromium.org> Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
2018-01-23 00:13:57 +01:00
if (!(a & (0xffU << 24))) {
lib: Unify log2() and related functions This patch adds a few bit counting functions that are commonly needed for certain register calculations. We previously had a log2() implementation already, but it was awkwardly split between some C code that's only available in ramstage and an optimized x86-specific implementation in pre-RAM that prevented other archs from pulling it into earlier stages. Using __builtin_clz() as the baseline allows GCC to inline optimized assembly for most archs (including CLZ on ARM/ARM64 and BSR on x86), and to perform constant-folding if possible. What was previously named log2f on pre-RAM x86 is now ffs, since that's the standard name for that operation and I honestly don't have the slightest idea how it could've ever ended up being called log2f (which in POSIX is 'binary(2) LOGarithm with Float result, whereas the Find First Set operation has no direct correlation to logarithms that I know of). Make ffs result 0-based instead of the POSIX standard's 1-based since that is consistent with clz, log2 and the former log2f, and generally closer to what you want for most applications (a value that can directly be used as a shift to reach the found bit). Call it __ffs() instead of ffs() to avoid problems when importing code, since that's what Linux uses for the 0-based operation. CQ-DEPEND=CL:273023 BRANCH=None BUG=None TEST=Built on Big, Falco, Jerry, Oak and Urara. Compared old and new log2() and __ffs() results on Falco for a bunch of test values. Change-Id: I599209b342059e17b3130621edb6b6bbeae26876 Signed-off-by: Patrick Georgi <pgeorgi@chromium.org> Original-Commit-Id: 3701a16ae944ecff9c54fa9a50d28015690fcb2f Original-Change-Id: I60f7cf893792508188fa04d088401a8bca4b4af6 Original-Signed-off-by: Julius Werner <jwerner@chromium.org> Original-Reviewed-on: https://chromium-review.googlesource.com/273008 Original-Reviewed-by: Patrick Georgi <pgeorgi@chromium.org> Reviewed-on: http://review.coreboot.org/10394 Tested-by: build bot (Jenkins) Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
2015-05-23 01:26:40 +02:00
r += 8;
a <<= 8;
}
lib/libgcc.c: Fix shift warnings ``` if (!(a & (0xffff << 16))) { ^~ src/lib/libgcc.c:40:18: error: result of '255 << 24' requires 33 bits to represent, but 'int' only has 32 bits [-Werror=shift-overflow=] if (!(a & (0xff << 24))) { ^~ src/lib/libgcc.c:45:17: error: result of '15 << 28' requires 33 bits to represent, but 'int' only has 32 bits [-Werror=shift-overflow=] if (!(a & (0xf << 28))) { ^~ ``` Change-Id: I7bdd75c20a76b303743d7e7e0d3a6503760284fd Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de> Reviewed-on: https://review.coreboot.org/c/23361 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Patrick Rudolph <siro@das-labor.org> Reviewed-by: Julius Werner <jwerner@chromium.org> Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
2018-01-23 00:13:57 +01:00
if (!(a & (0xfU << 28))) {
lib: Unify log2() and related functions This patch adds a few bit counting functions that are commonly needed for certain register calculations. We previously had a log2() implementation already, but it was awkwardly split between some C code that's only available in ramstage and an optimized x86-specific implementation in pre-RAM that prevented other archs from pulling it into earlier stages. Using __builtin_clz() as the baseline allows GCC to inline optimized assembly for most archs (including CLZ on ARM/ARM64 and BSR on x86), and to perform constant-folding if possible. What was previously named log2f on pre-RAM x86 is now ffs, since that's the standard name for that operation and I honestly don't have the slightest idea how it could've ever ended up being called log2f (which in POSIX is 'binary(2) LOGarithm with Float result, whereas the Find First Set operation has no direct correlation to logarithms that I know of). Make ffs result 0-based instead of the POSIX standard's 1-based since that is consistent with clz, log2 and the former log2f, and generally closer to what you want for most applications (a value that can directly be used as a shift to reach the found bit). Call it __ffs() instead of ffs() to avoid problems when importing code, since that's what Linux uses for the 0-based operation. CQ-DEPEND=CL:273023 BRANCH=None BUG=None TEST=Built on Big, Falco, Jerry, Oak and Urara. Compared old and new log2() and __ffs() results on Falco for a bunch of test values. Change-Id: I599209b342059e17b3130621edb6b6bbeae26876 Signed-off-by: Patrick Georgi <pgeorgi@chromium.org> Original-Commit-Id: 3701a16ae944ecff9c54fa9a50d28015690fcb2f Original-Change-Id: I60f7cf893792508188fa04d088401a8bca4b4af6 Original-Signed-off-by: Julius Werner <jwerner@chromium.org> Original-Reviewed-on: https://chromium-review.googlesource.com/273008 Original-Reviewed-by: Patrick Georgi <pgeorgi@chromium.org> Reviewed-on: http://review.coreboot.org/10394 Tested-by: build bot (Jenkins) Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
2015-05-23 01:26:40 +02:00
r += 4;
a <<= 4;
}
return r + four_bit_table[a >> 28];
}
#endif